To quantify performance gaps, we focus on ranking metrics, which are frequently used for evaluating clinical risk-stratification models. In this setting, clinicians aim to identify the top-\(k\)  patients to treat, where \(k\)  may be determined by resource constraints. To evaluate ranking performance gaps, we report two metrics: (1) the gap in within-group AUC and (2) the gap in cross-AUC (xAUC,  [1]}).
